Need help figuring this stern crack: gelcoat or laminate sheet?

[badadim]

Hello,


A small vertical crack appeared on the stern bent. It does not look like gelcoat cracking. It looks more like a seam or an edge of some sort of laminate or sheet covering the stern.

Any experience repairing similar structures and what is the best way of repairing it? I am trying to understand if I can just repair it locally by grinding and filling the impacted area or I need to remove the entire whatever sheet it is and replace it?

There is some bubbling around the area with in 1 foot from the crack since moisture is getting under. One of the pictures with the red arrow shows the exact location of the crack before it appeared.


Thank you!

[psk125]

Looks like you will need to grind it open to see exactly what’s going on and how far it goes. It could be just the gelcoat lifting, but “moisture getting under” needs to be investigated, and stopped, too. It is not likely that a “sheet” was used to build the transom- it is probably layers of mat and roving with gelcoat on the outside. Though it could be tabbing delaminating. This might be caused by excessive loads on the chock on your starboard quarter. Katabaic winds coming down off Mt. Douglas? Any cruise ships get loose in the marina? Neighbors with ham fists on their throttles bumping you?
Say hi to Eric & Maria up there.

[Toccata]

Possibly an old repair area, painted over. You can see cracks starting below and beside the main area that has opened up
Something has moved or moisture or extreme heat, Paint has lost its flex and cracked
Grind off the paint until you reach an area of well bonded paint and at that point feather the edge (of the paint)
Investigate the crack see if it extends into the substrate, treat/repair as required
Refair with a good fairing compound. Jotun 2 part filler is my "go to" product, Repaint
Usual old boat drama I'm afraid, wont be the last of it....smiley face!

[Dsanduril]

It looks like there is a plug in the teak directly above the crack. My guess would be that the screw under that plug needs to come out. Could be it wasn't pre-drilled enough and put enough pressure on the structure that it cracked, could be that water is getting in and did the same thing. Especially if you are anywhere near your homeport and got a freeze/thaw.

Even though it looks like a laminate, my guess is it is still gelcoat, but maybe popping with one/two layers of glass attached because the glass is delaminating from the inside. Pull the screw, then you can probably grind/fix/repair as per normal glass/gelcoat.